Arrangement at surge diverters for increasing the discharging ability



Aug. 26, 1952 s. vbR'rs EI'AL 2,608,600

ARRANGEMENT AT SURGE DIVERTERS FOR INCREASING THE DISCHARGING ABILITY Filed May 26, 1950 2 Sl-XEETSSHEET 1 HHOrmey Aug. 26, 1952 s. A. VORTS ET AL 2,608,600 ARRANGEMENT AT SURGE DIVERTERS FOR INCREASING THE DISCHARGING ABILITY Filed May 26, 1950 2 SHEETSSHEET 2 lrwenrors Y K J Patented Aug. 26, 1952 ARRANGEMENT AT INCREASING THE D 'Ludvika, Sweden,

SURGE DIVERTERS FOR 1 ISCHARGING ABILITY Svend Aage Viirts and Erland Bertil Nilsson,

assignors to Allmanna ""Svenska Elektriska Aktiebolaget, Vasteras, Sweiden', a Swedish corporation H r Application May 26, 1950, Serial No. 164,354 11,; j v In' Sweden June 1.8, 1.949

The present invention relates to electrical surge diverters with a plurality of series-connected spark gaps with voltage dependent resistors arranged in series with the spark gaps. Such a diverter should have on the one hand a voltage drop across the diverter caused by a certain current impulse, which voltage drop is as small as possible, and on the other hand the possibility of breaking the follow current, and on the third hand the ability of sustaining a plurality of repeated current impulses without being damaged. The first and the last requirements are fulfilled if the voltage dependent resistors in the diverter have a sufilciently large sectional area, because a large sectional area is followed by a large volume of the voltage dependent resistors and thus of a small specific current load, the voltage across the resistor thus being small, and the ability of enduring a plurality of repeated current impulses will be large.

In order to increase the discharging ability of a surge diverter, the nearest step would be to increase the sectional area of the voltage dependent resistors in the diverter, but as that area is increased, and at the same time the resistances are decreased, also the follow current will increase so that the spark gaps will no longer be able to break that current.

The present invention relates to a surge diverter having considerably larger discharging ability than diverters hitherto used. According to the invention, the diverter consists of two or several series of valve elements, 1. e. units consisting of spark gaps and voltage dependent resistors, corresponding elements in the different series then being mutually connected in parallel.

By such parallel connection of the valve elements, a lower resulting resistance is obtained at the same time as the specific current load on the spark gaps caused by the follow current will be the same, while by connecting the valve elements of the different series with each other through suitable impedances, all the valve elements connected in parallel will be functioning at every occurring over-voltage.

In the accompanying drawing, Figure 1 shows a surge diverter consisting of two series of valve elements arranged side by side, whereas Figure 2 shows a diverter intended for very high voltages consisting of three series of valve elements, the series being joined closely to each other at the top and placed at the corners of an equilateral triangle at the bottom.

The diverter shown in Figure 1 consists, as mentioned above, of two series of valve elements 1 Claim. (01. its-:20),

l arranged at the side-of-each other, each.ele ment consisting of an insulating cylinder 2 containing a series of spark gaps 3 and a pile of series-connectedresistance blocks 4 of a voltage dependent materials Thein'sulators 2, arranged above each other are closed at the ends by covers with flanges 5, also having the purpose of joining the insulators with each other. At the top flange 5, a metal ring 6 is attached in order to obtain a voltage equalising at the top part of the insulator piles. The two piles are jointd by a conductor 1 to which the line is connected, for instance at a terminal 8. The insulators 2 at the bottom only contain voltage dependent resistors, whereas the other insulators contain both resistors and spark gaps. As the voltage across the insulator pile, owing to the capacity conditions, is not evenly distributed, but upper than its lower part, the valve elements at the top contain more spark gaps 3 than the elements located below them. The joining flanges between the two uppermost elements are for instance connected with a high-ohmic resistor 9, enclosed in an insulator cylinder ID.

The arrangement acts in the following way:

If a suificiently high over-voltage strikes the top of the diverter, the spark gaps in at least one of the piles are ignited, for instance in the left pile, which means that the spark gaps in it are short-circuited by the arcs created. As long as the spark gaps in the right pile are not ignited, the point D has earth potential, whereas the points E. F and G have the voltages which are determined by the voltage drops in the resistances in the left pile. The flanges 5 between the two uppermost valve elements in the right pile therefore obtain a considerably high voltage through the agency of the resistor 9, on account of which the spark gaps in the next uppermost valve element in the right pile will be ignited. As, consequently, the voltage difference across the spark gaps in the top right valve element rises, also the spark gaps in this element are ignited. It is also evident that even if the spark gaps in the difierent piles have a tendency to ignite at different voltages, a simultaneous ignition will yet be ensured by the mutual connection through the resistor 9. The same effect will be obtained if the resistor 9 is replaced by a capaci tance of suitable magnitude.

In the form shown in Figure 2, the diverter consists of three piles H, l2, 13, at their lower ends fastened to the corners of a triangular frame H, whereas their upper ends are held together by a metal plate l5, also supporting a larger across its are reduced owing to the staying effect of the resistor elements I! and I8.

We claim as our invention: A lightning arrestor comprising piles of valve elements arranged side by side, said piles con- 1 sisting of spark gaps and voltage dependent resistances coupled in series, conducting elements coupling said piles in parallel and joining their upper and lower ends respectively, and an impedance element connecting the piles with each other at points between their upper and' lower ends. r u

SVEND AAGE VORTS. ERLAND BERTJL NILSSON.

4 REFERENCES CITED The following references are of record in the file of this patent:

Number Number UNITED STATES PATENTS Name Date Wurts Nov. 28, 1893 Mershon Apr. 13, 1909 Giles Oct. 8, 1912 Peek. Nov. 25, 1930 Ludwig Nov. 1, 1938 .Ackermann July 19, 1949 I Pittman May 9, 1950 FOREIGN PATENTS Country Date Germany Oct. 25, 1924 Great Britain Mar. 29, 1944 

